There are a variety of commercial operations wherein a fluid, e.g., a resin which is available in a source volume e.g., a few gallons, is moved under a first pressure to fill a closed dispensing reservoir; and then dispensed from that reservoir to a work site under carefully controlled conditions i.e., pressure and rate of output flow. The injection of a two component epoxy resin into structural cracks of a concrete structure to effect a permanent repair of the structure is an illustrative example of such commercial operations. A dispenser which meters and mixes the two components i.e., base resin and catalyst comprises a pair of transfer assemblies for handling the two components and a common output region where the outputs of the assemblies are mixed and delivered to the work site. Such a prior art dispenser is the CD3-A Dispenser which is marketed by Lily Corporation of Aurora, Ill. Each transfer assembly comprises: an input port, an input valve, a transfer chamber, a transfer input-output port, an output valve, and an output port. The input valves of the two assemblies are positioned opened and closed by a common input valve actuator; and similarly the output valves of the two assemblies are controlled by another common output valve actuator. In the CD3-A dispenser, the actuators are operated in sequence in accordance with locally produced control signals. It is important that the input valves are fully closed before the output valves are opened; and, upon completion of the dispensing of the mixture to the work site, the output valves must fully close before the input valves are opened. If the input and output valves remain simultaneously open, an improper mixture e.g., a mixture having a higher than normal catalyst level can reach the work site.